feat(fetch): add browser/node http client (#15)

Add browser/node support for fetching http request.

Author: enddynayn

lib/reader.js

@@ -12,6 +12,7 @@ const parquet_types = require('./types');
 const BufferReader = require('./bufferReader');
 const bloomFilterReader = require('./bloomFilterIO/bloomFilterReader');
 const groupBy = require("lodash/groupBy");
+const fetch = require('cross-fetch');
 
 const {
   getBloomFiltersFor,
@@ -125,8 +126,8 @@ class ParquetReader {
    * a `url` property.
    * This function returns a new parquet reader
    */
-  static async openUrl(request, params, options) {
-    let envelopeReader = await ParquetEnvelopeReader.openUrl(request, params, options);
+  static async openUrl(params, options) {
+    let envelopeReader = await ParquetEnvelopeReader.openUrl(params, options);
     return this.openEnvelopeReader(envelopeReader, options);
   }
 
@@ -136,7 +137,9 @@ class ParquetReader {
     }
     try {
       await envelopeReader.readHeader();
+
       let metadata = await envelopeReader.readFooter();
+
       return new ParquetReader(metadata, envelopeReader, opts);
     } catch (err) {
       await envelopeReader.close();
@@ -373,7 +376,7 @@ class ParquetEnvelopeReader {
     return new ParquetEnvelopeReader(readFn, closeFn, fileStat, options);
   }
 
-  static async openUrl(request, params, options) {
+  static async openUrl(params, options) {
      if (typeof params === 'string')
       params = {url: params};
     if (!params.url)
@@ -382,34 +385,23 @@ class ParquetEnvelopeReader {
     let base = params.url.split('/');
     base = base.slice(0, base.length-1).join('/')+'/';
 
-    params.encoding = params.encoding || null;
-
     let defaultHeaders = params.headers || {};
 
-    let filesize = async () => new Promise( (resolve, reject) => {
-      let req = request(params);
-      req.on('response', res => {
-        req.abort();
-        resolve(res.headers['content-length']);
-      });
-      req.on('error', reject);
-    });
+    let filesize = async () => {
+      
+      const { headers } = await fetch(params.url);
+      return headers.get('Content-Length');
+    };
 
-    let readFn = (offset, length, file) => {
+    let readFn = async (offset, length, file) => {
       let url = file ? base+file : params.url;
-
       let range = `bytes=${offset}-${offset+length-1}`;
       let headers = Object.assign({}, defaultHeaders, {range});
-      let req = Object.assign({}, params, {headers, url});
-      return new Promise( (resolve, reject) => {
-        request(req, (err, res) => {
-          if (err) {
-            reject(err);
-          } else {
-            resolve(res.body);
-          }
-        });
-      });
+      const response = await fetch(url, { headers });
+      const arrayBuffer = await response.arrayBuffer();
+      const buffer = Buffer.from(arrayBuffer);
+    
+      return buffer;
     };
 
     let closeFn = () => ({});
@@ -436,6 +428,7 @@ class ParquetEnvelopeReader {
 
   readHeader() {
     return this.read(0, PARQUET_MAGIC.length).then(buf => {
+
       if (buf.toString() != PARQUET_MAGIC) {
         throw 'not valid parquet file'
       }
@@ -623,7 +616,9 @@ class ParquetEnvelopeReader {
     if (typeof this.fileSize === 'function') {
       this.fileSize = await this.fileSize();
     }
+
     let trailerLen = PARQUET_MAGIC.length + 4;
+
     let trailerBuf = await this.read(this.fileSize - trailerLen, trailerLen);
 
     if (trailerBuf.slice(4).toString() != PARQUET_MAGIC) {